System of electrical distribution.



. y R. BRAUN.

SYSTEM OF ELECTRICAL DISTRIBUTION. '1 APPLICATION TILED 0012a, 1906. 924,628, Patented June 15,1909.

3 SHEETS-SHEET 1,

oumouu WITNESSES: I INVENTOR I ATTORNEY NORRIS FETEHS. INC LITHOY, WASHINGTON, D

R. BRAUN.

SYSTEM OF ELECTRICAL DiSTRIBUTION. APPLICATION FILED OCT. s, 1906.

Patented June 15, 1909.

3SHEE'I'S-SHEET 2 WITNESSES! gidm Q44 (6. Z-u /v-w- 7ATTORNEY R. BRAUN.

SYSTEM or ELECTRICAL DISTRIBUTION.

7 APPLICATION FILED OUT. 3, 1906. 924,628, Patented June 15, 1909.

3 SHEETS-SHEET 3.

V V V V v noun 0000000 I I I 5 1M I O O O 0 0 O O O O 0 O INVENTOR connections of a loan. '1-

RUDOLF BRAUN, OF MANCHESTER, ENGLAND, T6 WESTINGHOUSE ELECTRIC MANUFACTURING GQMPAHY, A GQRltftlfitffilON 0F FENNSYLVANEA.

caterers @F EEEQ ERZAE No. ceases.

Specification of Lette at'6nt. Patented June to, acne.

Application filed Gctoher 3, recs. serial No. 387,291.

To all whom it may concern:

tribution, of which'the following is aisfpeiiifi-- cation.

This invention relates to systems of eiectrical distributioin and, in particular," to." polyphase systems; where the :real and in ductive load is variable, whichiis the'case,

for example, when induction motors are connected to the circuit. If these are of large size, as for instance,' when used for the operation of winding engines or rolling mills, the load factorpf the power station and also the total eficiency of the power plant will be rather small. Moreover, the variations the voltage of the alternating current generators in the power station is considerable when an induction motor oflarge capacity is installed.

The objectjoi the' present invention is, to avoid these difiiculti es by equalizing the variable load of'the supply circuit and transforming it-into a constant load on the power station and by minimizing thevoltage variations so that, with a variable load on the supply circuit, the alternating current voltage of tlg e generators can be maintained substantially constant or, with overloads, be even automatically increased in a. desired degree. I

According to this invention,.a'r otary con- 'verter is connected across the transrnission conductors between the power station and the sirpplycircuit. This machine will run at a constant speed which will depend upon the frequency of the circuit, and its direct current side is electrically connected to a direct current shunt wound dynamo-electric machine designed for the same voltage as the direct cement side of the rotary converter. The shunt wound machine is conplea to a heavy fly-wheel and is constructed to run at as high a speed as possible, a suit-- able rheostat being included in its field magnet circuit.

This invention is, for the purpose of illustration, shown as applied to a three-phase system, in the accompanying drawings, of which-- Figure 1 is a dia ruumatic view of the ualizer or anged to electrical e Abe manually regulated. Fig. 2 is a similar diagram of a modification in which the regu- '-'lation is automat c, and Fig. 3 1s a die. "ram similarto F 2 showing another modificat-ion.

Reierri'ng now to Fig. l, the source 1 of .s three-phase conductors 1 which CQHEQLZIJ it to. a load consisting of one or more motors or other translating devices 2. The primary winding 3 of a three-phase transformefor set of transformers 4 is connected throu h a switch 5 in any well known way to the inc 1 at a point intermediate the load and the. generator 2, the secondary winding 6 of the transformer 4 being con nected to slip rings 7 on the alternating current side of the rotary converter 8. The latter is provided with a shunt winding 9 and a series winding 10, the winding 9 being provided with a rheostat 17. current brushes ll of the rotary converter are connected to the brushes 12 of a shunt wound direct current machine 13 which is provided with a fiy-wheel 1 the shunt-field winding 15 of machine 13 being connected through a rheostat 16.

'The operation of the system is as follows: When the rotary converter 8 is started and connected to the polyphase circuit 1, the shunt wound machine 13 wil-l also start in the ordinary way as a motor until it reaches a speed corresponding to the excitation of its field; that is, a speed at which the counterelcctromotive force at the brushes 12 is approximately equal to theelectromotive force at the brushes l1, and when this point is reached, a small current only, corresponding to the noload losses of the machine 13, will flow between the brushes ll of the rotary converter 8 and the brushes 12. If the field excitation of the machine 13 is then increased it will produce (at this speed) a higher electromotive force at the brushes 12 than at the rotary converter brushes 11 and the inachine 13 will act as a direct current generator, the rotary converter heing'thus compelled to convert from direct current to alternating current. If the field excitation of the machine 13 is decreased, the electrometive force at the brushes 12 will be less than that at the brushes 11 and the machine 13 will run as a motor, the rotary converter then operating to convert from alternating to direct current. It is therefore possible, by

The direct is assumed to be at the lei'taltering the field excitation of the machine 13, which can be done by adjustment of the rheostat 16, to cause the rotary converter 8 either to talre'power from the line 1 or to deliver power thereto. The function of the fiy-wheel 14: is to act as a reservoir of energy, its speed being decreased or increased according as the machine 13 is operating a generator or motor. The maximum speed of the fiy-wheel will thus correspond to the smallest-field excitation of the machine 13 which can be produced bythe regulator, and

the minimum speed of the fly-wheel will be that corresponding to the greatest possible field excitation of this machine. It is evidently possible to vary the speed of the flywheel inthis wayv to a very considerable extent, and, consequently, a smaller fly-wheel may be employed than is necessary with other systems-designed for service similar to that of the present invention.

()Wing tothe fact that the machine 13 may be arranged to rotate at a very high speed, 1ts field frame may be quite small, and an increase in size to allow for a larger variation 1 of the total flux may be obtained without undue expense.

In order to obtain a variation of both the power factor and voltage in the transmission circuit, the rotary converter 8 has its field magnet provided with both shunt and series windings. The series windings 10 is i in such a manner that its ampere tur I oppose the ampere turns of the shunt ding 9 whenthe converter is opera-til transform alternating current to direct current, and the resultantampere turns are preferably made suificient to have the rotary converter act under these conditions with 100 per cent. power factor at full load. When the converter is operating to transform from direct current to alternating livercd to the supply circuit and will relieve the generator, in any desired degree, of wattless load at the load; 2. The series winding 10 is arranged to have such a number of turns as will, in the manner outlined above, maintain the power factor of the load on the station, and therefore-the station voltage, very nearly constant, notwithstanding that the load of the supply circuit and its power factor may vary within wide limits.

In order that the regulation may be automatic, the field magnet excitation of. the shunt machine 13 must be varied in accordance with the magnitude and nature of the 'in which the general construction of the load equalizer is the same as in Fig. 1, but an automatic regulating device 18 is connected in series with the shunt winding 15 of the direct current machine 13. In addition to this, a hand regulating startingv resistance 19 and field rheostate 16are provided, which, however, are not usually operated when the machine is running. The automatic regulator 18 consists of a liquid'resistance contained in a tank 20,-the amount of resistance interposed in the circuit being determined by the distance apart of two electrodes 21 and 22 connected in the circuit of the shunt field magnet winding 15. One electrode 21 is fined while the other electrode 22 is arranged to be moved by a magnetic device 23.

This magnetic device may be any form of suitable alternating current motor, and in Fig. 2 is shown, for example, as a small induction motor, the rotor of which tends to move the electrode 22 toward the electrode 21 against the action of a spring-'26 when the primary winding .of the motor is energized, The primary windingof the motor is connected, through a switch 27, to a set of series transformers 28 connected in the supply circuit 2, so that the torque tending to reduce the distance between the electrodes 21 and 22 is proportional to the load on the circuit. it will be readily understood that the motor 23 may be replaced-by a wattmeter device, if desired, in which case shunt transformers connectedacross the supply circuit may also be required.

Fig. 3 shows another method of varying the excitation of the shunt field magnet of the directcurrent machine, so as to obtain automatic regulation, in which the general connections are the same as those shown in Fig. 2. The rotary converter 8 is provided with a rectifying device 31 comprising-a pair of slip rings 32 connected to a commutator 33. The slip rings are provided with brushes connected to the terminals of the secondary winding of aseries' transformer or set of transformers 35 connected in one of the supply circuits. The commutator is provided with brushes 36, 3 a of which the brush 3fi is connected to the brush 12 of the direct current machine 13, and the other brush 36 is connected, through an adjustable rheostat to one terminal of the shunt field winding 15, the other terminal of which is conneeted to the brush 12 or to the brush 1.-. The connnutator 33 is thus connected in series with the shunt field magnet winding drawing, the regulator 88 being so mechan ically coupled to the rotor of the machine 13 as to increase the resistance in the field iagnet circuit with increase of speed.

The operation of the apparatus is as follows: If no current is flowing in the supply circuit, the excitation of the field magnet finding of the direct current machine 13- will depend only on the regulator 38," and will thus decrease as the speed increases, so that the counter electromotive force generated at the brushes 12, 12*, will not increase proportionately to the increase of speed. Since aconstant direct current voltage is impressed on the brushes 12, 12 from the brushes 11, 11 of the rotary converter 8, he rotor andfiy-wheel of the machine 13 will continue to accelerate until all the resistance of the rheostat 37 has been interposed in the shunt field-magnet winding circuit. The machine 13 will then be running at its maximum speed. When load comes on the supply circuit, the field magnet ex: citation of the machine 13 will be increased in proportion to the load, as explained above, and the voltage at the brushes 12, 12 will consequently rise above the voltage at the brushes 11, 11*, and energy will be supplied to the circuit through the rotary converter until the speed of v the fly-wheel has been sufliciently reducedtto once more equalize the voltages at the brushes 12, 12, and 11,.11 In this condition;-that is, with full load on the supply circuit,a portion only of the resistance 37 of the-rheostat will, be in circuit with the shunt field magnet winding 15; the rotor of the machine will then be rotating at a speed corresponding to the excitation of its field, and will continue to run at that speed so long as full load'on the circuit continues.

machine 13 to operate as a generator, while any decrease of load will enable the speed of the machine to be increased.

It will be evident from the above that many variations from the methods of carryng out the invention .herem described may be made without departing from the essential idea, and such descriptions are given by Any increase of load will increase the field excitation, and cause the way of illustration only, and not by way of limitation.

I claim as my invention:

1. A. load equalizer for an alternating current supply circuit comprising a rotary converter the alternating current winding of which is connected across the supply circuit at a point between the power station and the load, a shunt-wound direct current machine the brushes of which areconnected to the direct current brushes of the rotary converterand the rotor of which is provided with a fiy-wheel, and means for causing said machine to operate either as a motor or as a generator and at variable speeds in accordance with the load on the supply circuit, Eubstantially as and for the purpose speci- 2. The combination with a main circuit, of a compound wound rotary converter having its alternating current end connected to said circuit between the generator and the load, a shunt wound direct current dynamoelectric machine having its armature electrically connected to the armature of the rotary converter, and means for varying the resistance of the shunt-field magnet circuit of each machine; I v

3. The combination with a main circuit, of an equalizer comprising a compound wound rotary convert-er, a direct current dynamo-electric machine electrically coupled thereto and provided with a fly-wheel, and means for. varying the resistance of the field magnet circuit of each of said machines.

4:. The combination with a main, circuit,

of an equalizer comprising a rotary-con chine as the load on the main circuit varies.

means for automatically varying the field strength of one or both ,of said machines as theload on the main circuit varies.

In testimony whereof, I vhave hereunto subscribed my name this 6th day. of September 1906.

RUDOLF BRAUN. Witnesses:

Vic-rota SCHNEIDER,

Max 

